Natural "Berber" wool yarns have long been the standard in the carpet, upholstery, apparel, etc., industries for producing high quality woven, knitted, or tufted wool fabrics or carpets having a natural blended heather coloration and "Berber" accent colors.
"Berber" wool yarns and carpets or fabrics produced therefrom date back to a time before Christ when Berber tribesmen in the deserts of North Africa produced fabrics or carpets from hand-made natural wool yarns spun from the normally-occurring varying staple lengths of naturally colored wool fibers of blacks, browns, grays, whites and other similar colors with normally-occurring very short staple length fibers in small clumps of darker colors of blacks and browns. When these fibers were spun into yarns by the Berber tribesmen, a yarn was produced which had a blended effect of the first mentioned colors, which have come to be called "heather" colors, with dots or specks of darker colors, which have come to be called "Berber" accent colors or dots.
In more recent times, "Berber" wool fabric or carpet yarns have been produced in the textile industry utilizing the "woolen system" of producing yarns. In this system, natural wool fibers having staple lengths from about 1/4 inch up to about 6 inches and mixed together are carded into slivers and taken directly off of the carding machine to spin yarns from the slivers without subsequent draftings or doublings of the yarns which would cause loss of the very short staple length fibers. The naturally-occurring small clumps of very short staple length fibers, which ultimately produce the "Berber" accent colors or dots in the yarns, must be retained in these "Berber" wool carpet yarns and, therefore, the woolen system of producing yarns is the only system of textile yarn production which is available.
However, due to the high cost of natural wool, these yarns are very expensive and, inasmuch as the resulting yarns include varying and very short staple length fibers, the yarns do not necessarily have desired characteristics from the standpoint of strength, crush resistance, wear resistance, stability, etc.
These latter desired characteristics can be obtained utilizing synthetic yarns, particularly continuous filament yarns and to a lesser degree long cut staple length fiber yarns. As is well known, continuous filament yarns are not separately spun as such but are produced directly out of the spinerette of the extrusion apparatus. On the other hand, long staple synthetic fiber yarns are produced on the "modified worsted system" of yarn production. In this system, long cut staple lengths of synthetic fibers, around 6 to 81/2 inches long, are blended, carded, drafted, doubled and then spun to produce yarns. The "modified worsted system" was designed specifically for long cut staple length synthetic yarns and is an off-shoot or modification of the older "worsted system" for wool yarns.
The "worsted system" differs from the "woolen system", discussed above, inasmuch as the wool slivers from the carding machine in the worsted system are combed to remove "noils" or very short staple length fibers to produce what is termed "top" of the longer staple length fibers which are then drafted, doubled and spun to make high quality worsted yarns for apparel fabric and the like.
Neither of these systems, i.e. the "worsted system" for wool or the "modified worsted system" for long cut staple length synthetic fibers, could be utilized to produce "Berber" wool yarns inasmuch as they utilize combing and/or drafting and doubling operations which could not be utilized when it is desired to retain the small clumps of very short staple length wool fibers which provide the "Berber" accent colors or dots which are distinctive to "Berber" wool yarn and carpets produced therefrom.
Attempts to simulate natural "Berber" wool yarns by the use of synthetic fibers have been attempted by others in utilizing acrylic or other synthetic fibers cut into varying staple lengths and stock dyed prior to blending and carding with the heather colors of natural wool and cutting very short staple length fibers to produce small clumps of such fibers which are stock dyed with the "Berber" accent colors and blended in with the other stock dyed fibers to be processed into a yarn on the "woolen system". While acrylic or other synthetic fiber yarns produced in this manner satisfactorily simulate the aesthetic appearance of natural "Berber" wool yarns and are much less expensive since synthetic fibers are cheaper than natural wool fibers, the resulting yarns and fabrics or carpets produced therefrom lack the desired strength and other characteristics of continuous filament or long staple length spun yarns. Additionally, the small clumps of "Berber" accent colored fibers in carpets produced from these types of synthetic yarns will easily come out of the carpet or fabric since they are very short and synthetic fibers do not have the natural kink or curliness of wool fibers and, therefore, do not adhere or are not locked into the wool fibers as would be the case with wool fibers.
It is now well recognized that nylon yarns are the superior synthetic yarns for use in carpet from a strength, soil resistance, crush resistance, etc., standpoint. However, nylon particularly tends to pill or ball up when present in very short cut staple lengths and, therefore, it is unsatisfactory for being utilized in the manner described above for acrylic fibers in producing simulated "Berber" yarns by stock dyeing and producing yarns on the "woolen system". In fact, the Federal Housing Administration will not approve carpets for federally financed housing wherein the carpet yarns have cut staple length spun nylon fibers of less than 6 inches in length.